Three-dimensional (3d) shoe blank made by double-bed flat knitting machine and manufacturing method thereof

ABSTRACT

A 3D shoe blank is an integral knit fabric without any sewn portion made by a double-bed flat knitting machine and includes an upper portion having two technical surfaces and knitted from at least a first yarn by skip-needle double-knitting, a front sole portion connected to the upper portion by a cast-on line and two connection lines to form a pocket structure, a rear portion connected to the front sole portion, and a heel portion extending from a center rear end of the rear portion. A portion of the front sole portion corresponding to the upper portion is knitted from at least a second yarn by skip-needle single-knitting. Two opposite sides of the heel portion are respectively connected to left and right rear ends of the rear portion to form a 3D rear shoe portion with two joining lines formed between the heel portion and the rear portion.

PRIORITY

The present invention claims priority to the Application No. 106118557 filed on Jun. 5, 2017 in Taiwan (ROC), which was entitled “3D Shoe Blank Made by Double-bed Flat Knitting Machine and Manufacturing Method Thereof”. All of which are hereby incorporated by reference as if fully set forth herein.

FIELD OF INVENTION

This invention generally relates to a three-dimensional (3D) shoe blank and a manufacturing method thereof. Specifically, the present invention relates to a 3D integral knitted shoe blank made by a double-bed flat knitting machine and a manufacturing method thereof.

BACKGROUND

In the conventional shoe-making process, a shoe is made by connecting multiple pieces of shoe parts. Consequently, the materials and the processes for manufacturing the shoes become very complicated. In recent years, owing to better permeability and comfort, less consumables required, and lower cost in the manufacturing process compared to conventional shoes, knitted shoes have quickly developed and gradually occupied a place in the market.

Knitted shoes are generally made by knitting yarns to form a shoe blank using the knitting machine and further attaching the shoe blank to the shoe sole. Here, the shapes of the shoe blanks formed by knitting are varied with the various types of knitting machines and knitting methods. Limited by the number of needle beds and current methods of knitting, two-needle-bed flat knitting machines commonly used in the industry generally knit and form a two-dimensional shoe blank in a sheet fabric form first, then the two-dimensional shoe blanks are further processed through seaming techniques to build a three-dimensional shape. However, due to the delicate and tedious seaming work required, it is hard to improve the production efficiency of the knitted shoes. In addition, two-dimensional shoe blanks usually only contain the part that covers the foot dorsal, resulting in lack of proper protection for the plantar, and such a two-dimensional shoe blank without the plantar part makes its conjugation and seaming with the shoe sole much more difficult.

SUMMARY OF THE INVENTION

In view of the prior art, it is an object of the invention to provide a 3D shoe blank made by using a double-bed flat knitting machine, wherein the 3D shoe blank is an integral knit fabric without any sewn portion, so the seaming work can be eliminated to greatly improve the production efficiency.

It is another object of the invention to provide a 3D shoe blank, whose upper portion is enhanced in structural strength by double-knitting to meet the needs of wearers.

In an embodiment, a 3D shoe blank made by using a double-bed flat knitting machine includes an upper portion, a front sole portion, a rear portion and a heel portion. The upper portion has two technical surfaces knitted from at least a first yarn by skip-needle double-knitting. The front sole portion is connected to the upper portion by a cast-on line and two connection lines, so the front sole portion and the upper portion are connected to form a pocket structure, wherein a portion of the front sole portion corresponding to the upper portion is knitted from at least a second yarn by skip-needle single-knitting. The rear portion is connected to the front sole portion. The heel portion extends from a center rear end of the rear portion. Two opposite sides of the heel portion are respectively connected to a left rear end and a right rear end of the rear portion, so the heel portion and the rear portion are combined to form a 3D rear shoe portion, and two joining lines are formed between the heel portion and the rear portion on the two opposite sides of the heel portion, respectively.

In an embodiment, the two connection lines are connected to two ends of the cast-on line and extend outward and obliquely toward an outer side of the 3D shoe blank.

In an embodiment, the upper portion substantially matches the front sole portion in shape and size.

In an embodiment, the 3D shoe blank further includes a first upper extension portion and a second upper extension portion connected to two sides of a rear end of the upper portion, respectively. The 3D shoe blank further includes a front sole extension portion connected between the front sole portion and the rear portion. The front sole extension portion partially corresponds to the first upper extension portion and the second upper extension portion.

In an embodiment, the font sole extension portion includes covered portions masked by the first upper extension portion and the second upper extension portion and an uncovered portion exposed between the first upper extension portion and the second upper extension portion. The covered portions are knitted from the second yarn by skip-needle single-knitting and the uncovered portion is knitted from the second yarn by single-knitting.

In an embodiment, the 3D shoe blank further includes an extension strap partially connected to the heel portion and extending outward toward the two opposite sides of the heel portion.

In an embodiment, the 3D shoe blank further includes an extension portion connected between the heel portion and the extension strap, so the extension strap is partially connected to the heel portion by means of the extension portion.

In another embodiment, the invention provides a method for knitting a three-dimensional (3D) shoe blank by using a double-bed flat knitting machine. The method includes providing at least a first yarn on a front needle bed and a back needle bed of the double-bed flat knitting machine by skip-needle double-knitting and providing at least a second yarn on the back needle bed together to form a cast-on line; knitting the first yarn on the front needle bed and the back needle bed continuing from the cast-on line by loop-transferring and skip-needle double-knitting to form an upper portion; knitting the second yarn on the back needle bed continuing from the cast-on line by skip-needle single-knitting to form a front sole portion, wherein the upper portion and the front sole portion are alternatingly knitted, and the front sole portion is connected to the upper portion to form a pocket structure; knitting continuing from the front sole portion on the front needle bed and the back needle bed to form a rear portion, wherein when forming the rear portion, a plurality of live stitches are preserved on the front needle bed at two sides of a rear end of the rear portion; and knitting continuing from a center of the rear end of the rear portion on the front needle bed and the back needle bed by double-knitting to form a heel portion with a predetermined number of stitches, wherein when the knitting of the heel portion reaches the predetermined number of stitches at two opposite sides of the heel portion, the back needle bed moves transversely to sequentially and respectively knit the live stitches preserved on the front needle bed at the two sides of the rear end of the rear portion together with the two opposite sides of the heel portion, so the heel portion and the rear portion are combined to form a 3D rear shoe portion

In an embodiment, the method further includes: knitting continuing from one side of a rear end of the upper portion by loop-transferring and skip-needle double-knitting to form a first upper extension portion; knitting a third yarn continuing from the other side of the rear end of the upper portion by loop-transferring and skip-needle double-knitting to form a second upper extension portion, wherein the first upper extension portion and the second upper extension portion are spaced apart and substantially symmetric, so the first upper extension portion, the second upper extension portion, and the upper portion are combined to form an upper assembly; and knitting the second yarn on the back needle bed to form a front sole extension portion between the front sole portion and the rear portion, wherein a portion of the front sole extension portion corresponding to the first upper extension portion and the second upper extension portion is knitted by skip-needle single-knitting, and another portion of front sole extension portion not corresponding to first upper extension portion and the second upper extension portion is knitted by single-knitting; the front sole portion and the front sole extension portion are combined to form a front sole assembly.

In an embodiment, the rear portion is knitted from the second yarn or another yarn, or the rear portion is knitted from the second yarn together with another yarn.

In an embodiment, the heel portion is knitted from the second yarn or another yarn, or the heel portion is knitted from the second yarn together with another yarn.

In an embodiment, the heel portion is knitted from the second yarn or another yarn, or the heel portion is knitted from the second yarn together with another yarn.

In an embodiment, the method further includes: after the 3D rear shoe portion is formed, double-knitting on the font needle bed and the back needle bed to form an extension strap, wherein the extension strap is partially connected to the heel portion and extends outward toward the two opposite sides of the heel portion.

In an embodiment, the method further includes: double-knitting from the heel portion on the font needle bed and the back needle bed to form an extension portion connected between the heel portion and the extension strap, so the extension strap is partially connected to the heel portion by means of the extension portion.

Compared to the prior art, the 3D shoe blank of the invention is an integral knit fabric without any sewn portion made by a double-bed flat knitting machine, so the seaming work can be omitted to simplify the manufacturing process. The 3D shoe blank of the invention has a strength-enhanced upper portion which is made by double-knitting and is beneficial to sustain the shape of the shoe body and meet the needs of wearers. The method of the invention utilizes an innovative knitting design to form an integral knit fabric just by using a double-bed flat knitting machine without upgrading the knitting machine, so the equipment cost can be effectively reduced and the production efficiency can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of a first embodiment of the three-dimensional (3D) shoe blank.

FIG. 2 is a schematic plan view of an upper portion of the 3D shoe blank of FIG. 1.

FIG. 3 is a schematic plan view of a front sole portion of the 3D shoe blank of FIG. 1.

FIG. 4 is a schematic plan view of a rear portion and a heel portion of the 3D shoe blank of FIG. 1.

FIG. 5 is a 3D schematic view of the first embodiment of the 3D shoe blank.

FIG. 6 is a 3D schematic view of a shoe body after the 3D shoe blank of FIG. 5 is molded.

FIG. 7 is a schematic plan view of a second embodiment of the 3D shoe blank.

FIG. 8 is a schematic plan view of an upper portion of the 3D shoe blank of FIG. 7.

FIG. 9 is a schematic plan view of a front sole portion of the 3D shoe blank of FIG. 7.

FIG. 10 is a schematic plan view of a rear portion and a heel portion of the 3D shoe blank of FIG. 7.

FIG. 11 is a 3D schematic view of the second embodiment of the 3D shoe blank.

FIG. 12 is a schematic cross-sectional view of the 3D shoe blank of FIG. 11.

FIG. 13 is a 3D schematic view of a shoe body after the 3D shoe blank of FIG. 11 is molded.

FIG. 14 is a schematic knitting diagram of the upper portion and the front sole portion of the 3D shoe blank according to an embodiment of the present invention.

FIG. 15 is a schematic knitting diagram of the upper extension portions and the front sole extension portion of the 3D shoe blank according to another embodiment of the present invention.

FIG. 16 is a schematic knitting diagram of the rear portion and the heel portion of the 3D shoe blank according to an embodiment of the present invention.

FIG. 17 is a schematic plan view of a third embodiment of the 3D shoe blank.

FIG. 18 is a 3D schematic view of the third embodiment of the 3D shoe blank.

FIG. 19 is a 3D schematic view of a shoe body after the 3D shoe blank of FIG. 18 is molded.

FIG. 20 is a schematic plan view of a fourth embodiment of the 3D shoe blank.

FIG. 21 is a 3D schematic view of the fourth embodiment of the 3D shoe blank.

FIG. 22 is a 3D schematic view of a shoe body after the 3D shoe blank of FIG. 21 is molded.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

For a thorough understanding of the invention, details of steps and structures of the invention will be described. Any manufacturing processes and specific steps of the knitting technique that are well known in the art will not be described in order not to impose undue limitations to the invention.

A three-dimensional (3D) shoe blank of the invention is an integral knit fabric without any sewn portion and made by using a double-bed flat knitting machine. For example, the 3D shoe blank can be knitted by using a double-bed flat knitting machine with movable cams, which can change the moving direction and drive the actions of the needles. As shown in FIG. 1 to FIG. 5, in a first embodiment, the 3D shoe blank 100 includes an upper portion 112, a front sole portion 122, a rear portion 130, and a heel portion 140. The upper portion 112 has two technical surfaces knitted from at least a yarn (such as the first yarn 10 shown in FIG. 14) by skip-needle double-knitting. That is, the outer surface of the upper portion 112 that faces outward and the inner surface of the upper portion 112 that faces the front sole portion 122 are both technical surfaces. Further, at least one yarn stated herein is preferably formed by twisting and combining multiple yarns with different characteristic (such as materials, types, shapes, colors and so on), but it is not limited thereto.

The front sole portion 122 is connected to the upper portion 112 by a cast-on line 101 and two connection lines 102, 103, so the front sole portion 122 and the upper portion 112 are connected to form a pocket structure. The portion of the front sole portion 122 that corresponds to the upper portion 112 is knitted from at least a yarn (such as the second yarn 20 shown in FIG. 14) by skip-needle single-knitting. For example, the front sole portion 122 is preferably knitted by skip-needle single-knitting from at least a yarn that is different from the yarn used for the upper portion 112, but not limited thereto. In this embodiment, the front sole portion 122 substantially completely corresponds to the upper portion 112, so the entire front sole portion 122 is knitted by skip-needle single-knitting. In other words, the upper portion 112 substantially matches the front sole portion 122 in shape and size. The upper portion 112 and the front sole portion 122 completely overlap each other and are connected to form a pocket-like structure. The front sole portion 122 and the upper portion 112 are connected at outer perimeters, so the cast-on line 101 is located on the front end of the front sole portion 122 and the upper portion 112, and the connection lines 102 and 103 are respectively located at two opposite sides of the front sole portion 122 and the upper portion 112 with respect to the cast-on line 101. Specifically, the front ends of the front sole portion 122 and the upper portion 112 are connected by the cast-on line 101, while the two connection lines 102 and 103 are connected to two ends of the cast-on line 101 and extend outward and obliquely toward an outer side of the rear portion 130. For example, the connection line 102 is connected to the left end of the cast-on line 101 and extends rearward to connect the left side edge of the upper portion 112 and the left side edge of the front sole portion 122. The connection line 103 is connected to the right end of the cast-on line 101 and extends rearward to connect the right side edge of the upper portion 112 and the right side edge of the front sole portion 122. As such, the upper portion 112 and the front sole portion 122 are connected to form the pocket structure.

The rear portion 130 is connected to the front sole portion 122. In an embodiment, the rear portion 130 is preferably knitted from at least a yarn by double-knitting. In an embodiment, the rear portion 130 can be knitted from the yarns previously used (such as the yarns 10, 20) or another yarn that is additionally introduced. In another embodiment, the rear portion 130 can be knitted from the yarns previously used (such as the yarns 10, 20) together with another yarn. For example, the rear portion 130 can be knitted by continuing using the yarn of the upper portion 112, the yarn of the front sole portion 122, the yarns of the upper portion 112 and the front sole portion 122, or another yarn. Alternatively, the rear portion 130 can be knitted by using another yarn together with the yarn of the upper portion 112, the yarn of the front sole portion 122, or the yarns of the upper portion 112 and the front sole portion 122.

The heel portion 140 extends from a center rear end of the rear portion 130. Two opposite sides of the heel portion 140 are respectively connected to a left rear end and a right rear end of the rear portion 130, so the heel portion 140 and the rear portion 130 are combined to form a 3D rear shoe portion 100 a, and two joining lines 104 a and 104 b are formed between the heel portion 140 and the rear portion 130 on the two opposite sides of the heel portion 140, respectively.

In an embodiment. The heel portion 140 is preferably knitted by continuing using the yarn of the rear portion 130 by double-knitting.

As shown in FIG.6, after the knitting of the 3D shoe blank 100 is finished, without any seaming work, the 3D shoe blank 100 can be worn on the last and be molded to form a shoe body 1. For example, when the 3D shoe blank 100 is knitted, a thermoplastic yarn can be knitted simultaneously. When the 3D shoe blank 100 is processed to form the shoe body 1, since the thermoplastic yarn is thermal-curable, by thermal molding, the thermoplastic yarn can be melted to be uniformly distributed over the shoe body 1 and then hardened to support the shape of the shoe body 1. The material of the thermoplastic yarn can be any suitable thermal curable material including, but not limited to, nylon, polyester, acrylic, etc. It is noted that the shoe body 1 can be shaped by other methods, not limited to the use of thermoplastic yarn during the knitting process.

After the 3D shoe blank 100 is molded into the shoe body 1, the upper portion 112 and the front sole portion 122 can cover from the foot dorsal to the front plantar, while the 3D rear shoe portion 100 a constituted by the rear portion 130 and the heel portion 140 covers the lateral portion, the rear plantar, and the heel of the foot. Specifically, the rear edge of the upper portion 112 and the upper edge of the 3D rear shoe portion 100 a (i.e. the outer edges of the rear portion 130 and the heel portion 140) together define a shoe opening la of the shoe body 1 to allow the foot to enter the interior space enclosed by the shoe body 1. The connection lines 102 and 103 on two opposite sides of the front sole portion 122 and the upper portion 112 respectively start from two ends of the cast-on line 101 and extend gradually outward and obliquely toward the 3D rear shoe portion 100 a until reaching the shoe opening 1 a, so the front sole portion 122 preferably covers from the front plantar toward two opposite front lateral portions. For example, the upper portion 112 can cover the dorsal surface of the front foot, and the front sole portion 122 covers the front plantar and extends upward to cover the front lateral portions. Moreover, a portion of the rear portion 130 covers the rear plantar while another portion of the rear portion 130 extends upward to cover the rear lateral portions and extends rearward to cover the heel with the heel portion 140. Therefore, the shoe body 1 formed from the 3D shoe blank 100 of the invention can substantially cover the dorsal, the plantar, the lateral sides, and the heel of the foot.

In the first embodiment, although the 3D shoe blank 100 is illustrated with substantially completely overlapped upper portion 112 and front sole portion 122, but not limited thereto. In other embodiments, by changing the upper design, the 3D shoe blank may have a different outer appearance. As shown in FIG. 7 to FIG. 12, in a second embodiment, a shoe blank 200 includes an upper portion 212, a front sole portion 222, a rear portion 130, and a heel portion 140 and further includes a first upper extension portion 214 a, a second upper extension portion 214 b, and a front sole extension portion 224. Similarly, the upper portion 212 has two technical surfaces knitted from at least a yarn (such as the first yarn 10) by skip-needle double-knitting. The front sole portion 222 is connected to the upper portion 212 by a cast-on line 201 and two connection lines 202, 203, so the front sole portion 222 and the upper portion 212 are connected to form a pocket structure. The portion of the front sole portion 222 that corresponds to the upper portion 212 is knitted from at least a yarn (such as the second yarn 20) by skip-needle single-knitting. The first upper extension portion 214 a and the second upper extension portion 214 b are connected to two sides of a rear end of the upper portion 212, respectively. The front sole extension portion 224 is connected between the front sole portion 222 and the rear portion 130 and partially corresponds to the first upper extension portion 214 a and the second upper extension portion 214 b. The heel portion 140 extends from a center rear end of the rear portion 130. The two opposite sides of the heel portion 140 are respectively connected to a left rear end and a right rear end of the rear portion 130, so the heel portion 140 and the rear portion 130 are combined to form a 3D rear shoe portion 100 a, and two joining lines 104 a and 104 b are formed between the heel portion 140 and the rear portion130 on the two opposite sides of the heel portion 140, respectively. In this embodiment, details of the upper portion 212, the front sole portion 222, the rear portion 130, and the heel portion 140 can refer to the related descriptions of the embodiment of FIG. 1 and will not be elaborated again. Hereafter, the details of the first upper extension portion 214 a, the second upper extension portion 214 b, and the front sole extension 224 are illustrated.

Specifically, the first upper extension portion 214 a and the second upper extension portion 214 b are spaced apart and connected to two sides of the rear end of the upper portion 212 (such as left rear end and right rear end), so the first upper extension portion 214 a, the second upper extension portion 214 b, and the upper portion 212 are combined to form an upper assembly 210. In an embodiment, one of the upper extension portions 214 a and 214 b is preferably knitted by continuing knitting the yarn of the upper portion 212, and the other of the upper extension portions 214 a and 214 b is knitted by using another yarn (such as the third yarn 30 of FIG. 15), but not limited thereto. In another embodiment, the upper extension portions 214 a and 214 b can be knitted by using other yarns of the same attribute or amount. Moreover, the upper extension portions 214 a and 214 b are preferably symmetric in shape (i.e. the outer appearances thereof are substantially visually symmetric), but not limited thereto.

The front sole extension portion 224 is connected to the rear end of the front sole portion 222, so the front sole portion 222 and the front sole extension portion 224 are combined to form a front sole assembly 220. The front sole extension portion 224 partially corresponds to the first upper extension portion 214 a and the second upper extension portion 214 b. For example, the front sole extension portion 224 includes covered portions 224 a and 224 b and an uncovered portion 224 c. The covered portions 224 a and 224 b are masked by the first upper extension portion 214 a and the second upper extension portion 214 b, respectively. The uncovered portion 224 c is exposed between the first upper extension portion 214 a and the second upper extension portion 214 b. That is, the covered portions 224 a and 224 b preferably respectively match the upper extension portions 224 a and 224 b in shape and size, while the uncovered portion 224 c is located between the covered portions 224 a and 224 b and not masked by the upper assembly 210. The front sole portion 222 is preferably knitted by skip-needle single-knitting from at least a yarn that is different from the yarn used for the upper portion 212. The covered portions 224 a, 224 b of the front sole extension portion 224 are preferably knitted continuing from the yarn of the front sole portion 222 (such as the second yarn 20) by skip-needle single-knitting. The uncovered portion 224 c of the front sole extension portion 224 is preferably knitted continuing from the yarn of the front sole portion 222 (such as the second yarn 20) by single-knitting. When the front sole portion 222 is connected to the upper portion 212, the upper portion 212 and the front sole portion 222 substantially completely overlap each other, so the upper extension portions 214 a and 214 b substantially completely overlap the covered portions 224 a and 224 b of the front sole extension portion 224, respectively, while the uncovered portion 224 c of the front sole extension portion 224 is exposed by not overlapping the upper portion 212 and the upper extension portions 214 a and 214 b.

The front end of the upper portion 212 and the front end of the front sole portion 222 are connected by the cast-on line 201, while the two connection lines 202 and 203 are connected to two ends of the cast-on line 201 and extend outward and obliquely toward an outer side of the rear portion 130. For example, the connection line 202 is connected to the left end of the cast-on line 201 and extends rearward to connect the left side edge of the upper portion 212 and the left side edge of the front sole portion 222 and further to connect the left side edge of the first upper extension portion 214 a and the left side edge of the covered portion 214 a. The connection line 203 is connected to the right end of the cast-on line 201 and extends rearward to connect the right side edge of the upper portion 212 and the right side edge of the front sole portion 222 and further to connect the right side edge of the second upper extension portion 214 b and the right side edge of the covered portion 214 b. As such, the upper assembly 210 and the front sole assembly 220 are connected at outer perimeters to form the pocket structure.

It is noted that the thickness of the 3D shoe blank 200 in FIG. 12 is exaggerated for better understanding. In practical applications, the thickness of the 3D shoe blank 200 varies with the choice of the yarns, the knitting density, etc.

As shown in FIG. 13, after the knitting of the 3D shoe blank 200 is finished, without any seaming work, the 3D shoe bank 200 can be worn on the last and molded to form a shoe body 2. After the 3D shoe blank 200 is molded into the shoe body 2, the upper assembly 210 and the front sole assembly 220 can cover from the foot dorsal to the front plantar, while the 3D rear shoe portion 100 a constituted by the rear portion 130 and the heel portion 140 covers the rear lateral portions, the rear plantar and the heel of the foot. Specifically, the inner edges of the upper portion 212 and the upper extension portions 214 a and 214 b and the upper edge of the 3D rear shoe portion 100 a (i.e. the outer edges of the rear portion 130 and the heel portion 140) together define a shoe opening 2 a of the shoe body 2 to allow the foot to enter the interior space enclosed by the shoe body 2. The connection lines 202 and 203 respectively start from two ends of the cast-on line 201 and extend gradually outward and obliquely toward the 3D rear shoe portion 100 a until reaching the shoe opening 2 a, so the front sole assembly 220 preferably covers from the front plantar toward two opposite front lateral portions. For example, the upper portion 212 and the upper extension portions 214 a and 214 b can cover the dorsal surface of the front foot, and the front sole portion 122 and at least a portion of the font sole extension portion 224 (such as the uncovered portion 224 c) covers the front plantar, while at least a portion of the font sole extension portion 224 (such as the covered portions 224 a, 224 b) extends upward to cover the front lateral portions. Moreover, a portion of the rear portion 130 covers the rear plantar, while another portion of the rear portion 130 extends upward to cover the rear lateral portions and extends rearward to cover the heel with the heel portion 140. Therefore, the shoe body 2 formed from the 3D shoe blank 200 of the invention can substantially cover the dorsal, the plantar, the lateral sides, and the heel of the foot.

The 3D shoe blank 100 or 200 is preferably knitted by using the double-bed flat knitting machine with movable cams, which can change the moving direction and drive the actions of the needles. In an embodiment, the method for knitting the 3D shoe blank by using a double-bed flat knitting machine includes: providing at least a first yarn (such as the yarn 10) on a front needle bed and a back needle bed of the double-bed flat knitting machine by skip-needle double-knitting and providing at least a second yarn (such as the yarn 20) on the back needle bed together to form a cast-on line (such as 101, 201); knitting the first yarn on the front needle bed and the back needle bed by loop-transferring and skip-needle double-knitting to form an upper portion (such as 112, 212); knitting the second yarn on the back needle bed by skip-needle single-knitting to form a front sole portion (such as 122, 222), wherein the upper portion and the front sole portion are alternatingly knitted, and the front sole portion is connected to the upper portion to form a pocket structure; knitting continuing from the front sole portion on the front needle bed and the back needle bed to form a rear portion (such as 130), wherein when forming the rear portion, a plurality of live stitches (such as 31 a-38 a, 31 b-38 b) are preserved on the front needle bed at two sides of a rear end of the rear portion; and knitting continuing from a center of the rear end of the rear portion on the front needle bed and the back needle bed by double-knitting to form a heel portion (such as 140) with a predetermined number of stitches, wherein when the knitting of the heel portion reaches the predetermined number of stitches at two opposite sides of the heel portion, the back needle bed moves transversely to sequentially and respectively knit the live stitches preserved on the front needle bed at the two sides of the rear end of the rear portion together with the two opposite sides of the heel portion, so the heel portion and the rear portion are combined to form a 3D rear shoe portion (such as 100 a).

Hereafter, referring to FIGS. 14˜16 and FIG. 1 to FIG. 13, the method for knitting the 3D shoe blank 100 or 200 by using the double-bed flat knitting machine is illustrated. In an embodiment, the method includes: providing at least a yarn (such as the first yarn 10) on a front needle bed FB and a back needle bed BB by skip-needle double-knitting and providing at least another yarn (such as the second yarn 20) on the back needle bed BB together to form a cast-on line 101 (or 201). For example, as shown in FIG. 14, in step S10, from left to right, the first yarn 10 is knitted alternatingly on the front needle bed FB and the back needle bed BB with skipped needles (e.g. one stitch on the front needle bed FB, skipped needles on front and back needle beds FB & BB, one stitch on the back needle BB, then one stitch on the front needle bed FB, skipped needles on front and back needle beds FB, BB, one stitch on the back needle BB, and so on), and the second yarn 20 is continuously knitted on the back needle bed BB, so the first yarn 10 and the second yarn 20 together form the cast-on line 101 (or 201) on the front needle bed FB and the back needle bed BB. In other words, the skip-needle knitting refers to a knitting manner that a certain needles of at least one of the front needle bed FB and the back needle bed BB is missed or unused with no stitches thereon. For example, the skip-needle double-knitting refers to a knitting manner that is performed alternatingly on the front needle bed FB and the back needle bed BB with a certain needles thereof missed or unused with no stitches thereon. The skip-needle single-knitting refers to a knitting manner that is performed mainly on the front needle bed FB or the back needle bed BB with a certain needles thereof missed or unused with no stitches thereon. Moreover, it is noted that when forming the cast-on line 101 (or 201), the beginning and the end of the first yarn 10 and the second yarn 20 are preferably knitted on the front needle bed FB.

The method further includes: knitting the first yarn 10 on the front needle bed FB and the back needle bed BB continuing from the cast-on line 101 (or 201) by loop-transferring and skip-needle double-knitting to form an upper portion 112 (or 212), and knitting the second yarn 20 on the back needle bed BB continuing from the cast-on line by skip-needle single-knitting to form a front sole portion 122 (or 222), wherein the upper portion 112 (or 212) and the front sole portion 122 (or 222) are alternatingly knitted, and the front sole portion 122 (or 222) is connected to the upper portion 112 (or 212) to form a pocket structure. For example, as shown in step S11 of FIG. 14, during the first knitting period P1, reverse-knitting from right to left, by using the cam at the first order 401, the first yarn 10 is knitted alternatingly on the front needle bed FB and the back needle bed BB with skipped needles to connect the cast-on line 101 (or 201) and to form the upper portion 112 (or 212). In other words, the first yarn 10 is knitted according to the stitches thereof knitted on the front needle bed FB and the back needle bed BB in the previous step S10, so the upper portion 112 (or 212) is knitted alternatingly on the front needle bed FB and the back needle bed BB with skipped needles that are unused (i.e. skip-needle double-knitting). Then, by using the cam at the second order 402, a loop-transfer step is performed, so the stitches of the upper portion 112 are changed from a skipped alternating arrangement to a non-skipped arrangement. That is, the stitches formed by the first yarn 10 on the back needle bed BB is transferred to the non-occupied needles of the front needle bed FB (i.e. the skipped front needles) in the previous knitting. After the stitches of the upper portions 112 (or 212) are transferred, by using the cam at the third order 403, the second yarn 20 is knitted on the back needle bed BB by skip-needle knitting to connect the cast-on line 101 (or 201) and to form the front sole portion 122 (or 222). That is, after the loop-transfer, the second yarn 20 is knitted according to the stiches thereof on the back needle bed BB (i.e. two adjacent stitches on the back needle bed with one skipped needle in between), so the front sole portion 122 (or 222) is knitted by skip-needle single-knitting.

During the second knitting period P2 of the step S11, forward knitting from left to right, by using the cam at the first order 401, the second yarn 20 is knitted on the back needle bed BB by skip-needle single-knitting as described above to form another course of the front sole portion 122 (or 222). That is, according to the stitches of the front sole portion 122 (or 222) on the back needle bed BB, the front sole portion 122 (or 222) is knitted on the back needle bed BB and two adjacent stitches on the back needle bed BB with one skipped needle in between. Then, by using the cam at the second order 402, the loop-transfer step is performed to change the stitches of the upper portion 112 (or 212) from the non-skipped arrangement to the skipped alternating arrangement. That is, the loops previously transferred to the front needle bed FB are transferred back to their original positions on the back needle bed BB. After the stitches of the upper portion 112 (or 212) are transferred, by using the cam at the third order 403, the first yarn 10 is knitted by skip-needle double-knitting on the front needle bed FB and the back needle bed BB to form the upper portion 112 (or 212). That is, after the loop-transfer, the first yarn 10 is knitted according to the stitches of the upper portion 112 (or 212) on the front needle bed FB and the back needle bed BB to form a next course of the upper portion 112 (or 212). It is noted that during the knitting process, since the knitting direction alternates between forward and reverse, the order of the cams alternates accordingly. For example, during the second knitting period P2 of the step S11, the cam at the first order 401 is the cam at the third order 403 in the first knitting period P1, and the cam at the third order 403 is the cam at the first order 401 in the first knitting period P1. Since the cam at the second order 402 is arranged in the middle of the order, no matter it is in the forward or reverse knitting period, the order of the cam at the second order 402 remains the same.

During the third knitting period P3 of the step S11, reverse knitting from right to left, by using the cam at the first order 401 (i.e. the cam at the third order 403 in the second knitting period P2), the first yarn 10 is knitted by skip-needle double-knitting alternatingly on the front needle bed FB and the back needle bed BB to from the upper portion 112 (or 212). Then, by using the cam at the second order 402, the loop-transfer step is performed, so the stitches of the upper portion 112 (or 212) are changed from the skipped alternating arrangement to the non-skipped arrangement. That is, the stitches of the upper portion 112 (or 212) formed by the first yarn 10 on the back needle bed BB are transferred to the non-occupied needles of the front needle bed FB (i.e. the skipped front needles) in the previous knitting. After the stitches of the upper portions 112 (or 212) are transferred, by using the cam at the third order 403 (i.e. the cam at the first order 401 in the second knitting period P2), the second yarn 20 is knitted on the back needle bed BB by skip-needle single-knitting to form a next course of the front sole portion 122 (or 222).

During the fourth knitting period P4 of the step S11, forward knitting from left to right, by using the cam at the first order 401 (i.e. the cam at the third order 403 in the third knitting period P3), the second yarn 20 is knitted on the back needle bed BB by skip-needle single-knitting as described above to form another course of the front sole portion 122 (or 222). Then, by using the cam at the second order 402, the loop-transfer step is performed to change the stitches of the upper portion 112 (or 212) from the non-skipped arrangement to the skipped alternating arrangement. That is, the loops of the upper portion 112 (or 212) previously transferred to the front needle bed FB are transferred back to their original positions on the back needle bed BB. After the stitches of the upper portion 112 (or 212) are transferred, by using the cam at the third order 403 (i.e. the cam at the first order 401 in the third knitting period P3), the first yarn 10 is knitted by skip-needle double-knitting alternatingly on the front needle bed FB and the back needle bed BB to from another course of the upper portion 112 (or 212). That is, the knitting in the fourth knitting period P4 is substantially the same as the knitting in the second knitting period P2. By repeating the knitting in the second knitting period P2 and the third knitting period P3 of the step S11, the upper portion 112 (or 212) and the front sole portion 122 (or 222) can be alternatingly knitted until the formation of the upper portion 112 (or 212) and the front sole portion 122 (or 222) is completed. Specifically, by repeating the knitting in the second knitting period P2 and the third knitting period P3 of the step S11, the pocket structure constituted by the upper portion 112 and the front sole portion 122 of the 3D shoe blank 100 in FIG. 1 or the pocket structure constituted by the upper portion 212 and the front sole portion 222 of the 3D shoe blank 200 in FIG. 2 can be formed.

When forming the 3D shoe blank 200 of FIG. 7, the method further includes: knitting continuing from one side of a rear end of the upper portion 212 by loop-transferring and skip-needle double-knitting to form a first upper extension portion (such as 214 a); knitting a third yarn (as shown in FIG. 15) continuing from the other side of the rear end of the upper portion 212 by loop-transferring and skip-needle double-knitting to form a second upper extension portion (such as 214 b), wherein the first upper extension portion 214 a and the second upper extension portion 214 b are spaced apart and substantially symmetric, so the first upper extension portion 214 a, the second upper extension portion 214 b, and the upper portion 212 are combined to form the upper assembly 210; and knitting the second yarn 20 on the back needle bed BB to form a front sole extension portion (such as 224) between the front sole portion 222 and the rear portion 130, wherein a portion of the front sole extension portion 224 corresponding to the first upper extension portion 214 a and the second upper extension portion 214 b (such as covered portions 224 a, 224 b) is knitted by skip-needle single-knitting, and another portion of the front sole extension portion 224 not corresponding to the first upper extension portion 214 a and the second upper extension portion 214 b (such as the uncovered portion 224 c) is single-knitted, so the front sole portion 222 and the front sole extension portion 224 are combined to form the front sole assembly 220.

For example, as shown in FIG. 15, in an embodiment, a step S12 of forming the upper extension portions 214 a and 214 b and the front sole extension portion 224 includes: during the first knitting period P1, forward knitting from left to right, by using the cam at the third order 403, the first yarn 10 is knitted by skip-needle knitting alternatingly on the front needle bed FB and the back needle bed BB to form a course of the first upper extension portion 214 a. As such, the first upper extension portion 214 a is connected to the left rear end of the upper portion 212 by space double-knitting.

The step S12 further includes: during the second knitting period P2, reverse knitting from right to left, by using the cam at the first order 401, a third yarn 30 is provided at the left rear end of the upper portion 212 and knitted by skip-needle double-knitting alternatingly on the front needle bed FB and the back needle bed BB to form a course of the second upper extension portion 214 b. As such, the second upper extension portion 214 b is connected to the right rear end of the upper portion 212 and knitted by space double-knitting as described above. Then, by using the cam at the second order 402, the loop-transfer step is performed to change the stitches of the upper extension portions 214 a and 214 b from the skipped alternating arrangement to the non-skipped arrangement. That is, the stitches of the upper extension portions 214 a and 214 b formed by the first yarn 10 and the third yarn 30 on the back needle bed BB is transferred to the corresponding non-occupied needles of the front needle bed FB (i.e. the skipped front needles) in the previous knitting. After the loop-transfer, by using the cam at the third order 403, the second yarn 20 of the front sole portion 222 is knitted by skip-needle single-knitting at a location corresponding to the second upper extension portion 214 b on the back needle bed BB to form the right covered portion 224 b, continuously single-knitted at a location corresponding between the upper extension portions 214 a and 214 b on the back needle bed BB to form the uncovered portion 224 c, and then knitted by skip-needle single knitting at a location corresponding to the first upper extension portion 214 a on the back needle bed BB to form the left covered portion 224 a, so the left covered portion 224 a, the uncovered portion 224 c, and the right covered portion 224 b together form the front sole extension portion 224, which is connected to the rear end of the front sole portion 222.

During the third knitting period P3 of the step S12, forward knitting from left to right, by using the cam at the first order 401 (i.e. the cam at the third order in the second knitting period P2), the second yarn 20 is knitted by skip-needle single-knitting at a location corresponding to the first upper extension portion 214 a on the back needle bed BB to form another course of the left covered portion 224 a, continuously single-knitted at a location corresponding between the upper extension portions 214 a and 214 b on the back needle bed BB to form another course of the uncovered portion 224 c, and then knitted by skip-needle single-knitting at a location corresponding to the second upper extension portion 214 b on the back needle bed BB to form the right covered portion 224 b, so another course of the front sole extension portion 224 is knitted. Then, by using the cam at the second order 402, the loop-transfer step is performed to change the stitches of the upper extension portions 214 a, 214 b from the skipped alternating arrangement to the non-skipped arrangement. That is, the loops of the upper extension portions 214 a and 214 b previously transferred to the front needle bed FB are transferred back to their original positions on the back needle bed BB. After the loop-transfer, by using the cam at the third order 403 (i.e. the cam at the first order in the second knitting period P2), the first yarn 10 is knitted by skip-needle double-knitting alternatingly on the front needle bed FB and the back needle bed BB to from another course of the first upper extension portion 214 a, and the third yarn 30 is knitted by skip-needle double-knitting alternatingly on the front needle bed FB and the back needle bed BB to form another course of the second upper extension portion 214 b.

During the fourth knitting period P4 of the step S12, reverse knitting from right to left, by using the cam at the first order 401 (i.e. the cam at the third order 403 in the third knitting period P3), the third yarn 30 is knitted by skip-needle double-knitting alternatingly on the front needle bed FB and the back needle bed BB to from another course of the second upper extension portion 214 b, and the first yarn 10 is knitted by skip-needle double-knitting alternatingly on the front needle bed FB and the back needle bed BB to from another course of the first upper extension portion 214 a. Then, by using the cam at the second order 402, the loop-transfer step is performed to change the stitches of the upper extension portions 214 a, 214 b from the skipped alternating arrangement to the non-skipped arrangement. That is, the stitches of the upper extension portions 214 a, 214 b respectively formed by the first yarn 10 and the third yarn 30 on the back needle bed BB are transferred to the corresponding non-occupied needles of the front needle bed FB (i.e. the skipped front needles) in the previous knitting. After the loop-transfer, by using the cam at the third order 403 (i.e. the cam at the first order 401 in the third knitting period P3), the second yarn 20 of the front sole portion 222 is knitted by skip-needle single-knitting at a location corresponding to the second upper extension portion 214 b on the back needle bed BB to form the right covered portion 224 b, continuously single-knitted at a location corresponding to the space between the upper extension portions 214 a and 214 b on the back needle bed BB to form the uncovered portion 224 c, and then knitted by skip-needle single-knitting at a location corresponding to the first upper extension portion 214 a on the back needle bed BB to form the left covered portion 224 a, so another course of the front sole extension portion 224 is knitted. Accordingly, by repeating the third knitting period P3 and the fourth knitting period P4 of the step S12, the knitting of the upper extension portions 214 a, 214 b and the front sole extension portion 224 can be completed, so the first upper extension portion 214 a, the second upper extension portion 214 b, and the upper portion 212 together form the upper assembly 210, and the front sole extension portion 224 and the front sole portion 222 together form the front sole assembly 220. As such, the upper assembly 210 and the front sole assembly 220 partially corresponds to each other to form a pocket structure. The upper assembly 210 (including the upper portion 212 and the upper extension portions 214 a and 214 b) formed by such skip-needle double-knitting can have two technical surfaces to enhance the structural strength of the upper assembly 210. The portion of the front sole assembly 220 that corresponds to the upper assembly 210 (such as the front sole portion 222 and the covered portions 224 a and 224 b) has a skipped single-knitted structure, while the portion of the front sole assembly 220 that does not correspond to the upper assembly 210 (such as the uncovered portion 224 c) has a single-knitted structure.

It is noted that the number of stitches of the upper extension portions 214 a and 214 b can be changed (such as gradually reduced or increased) during the knitting process to increase the variety of the upper assembly 210.

In an embodiment, referring to FIG. 16, a step of forming the 3D rear shoe portion 100 a of FIG. 4 or FIG. 10 is illustrated. For example, after the formation of the upper portion 112 and the front sole portion 122 of FIG. 1 or after the formation of the upper assembly 210 and the front sole assembly 210 of FIG. 7, the method includes: knitting continuing from the rear end of the front sole portion 122 (or the font sole extension portion 224) on the front needle bed FB and the back needle bed BB to form the rear portion 130. As described above, the yarn used for knitting the rear portion 130 may include the first yarn 10, the second yarn 20, and/or the third yarn 30, or another yarn. Alternatively, the yarn used for knitting the rear portion 130 may include the first yarn 10, the second yarn 20, and/or the third yarn 30 together with another yarn. In this embodiment, the yarns 10 and 20 continue to be knitted back and forth from left to right or from right to left on the front needle bed FB and the back needle bed BB to form the rear portion 130, so the rear portion 130 is connected to the rear end of the front sole portion 122 (or the front sole extension portion 224).

The heel portion 140 may be knitted from the yarns previously used (such as 10, 20, 30) or another yarn. Alternatively, the heel portion 140 may be knitted from the yarns previously used (such as 10, 20, 30) together with another yarn. For example, after forming the rear portion 130, the yarns 10 and 20 are knitted on the front needle bed FB and the rear needle bed BB from the left side of the rear portion 130 toward the center of the rear portion 130 to form a predetermined number of stitches of the heel portion 140, and a plurality of live stitches (such as 31 a-38 a) are preserved on the front needle bed FB at the right side of the rear end of the rear portion 130. It is noted that when the heel portion 140 reaches the predetermined number of stitches on the right border, the location of the rightmost stitch 41 a of the heel portion 140, which is to be knitted, corresponds to the location of the innermost (i.e. leftmost) live stitch 31 a of the live stitches 31 a-38 a preserved at the right rear end of the rear portion 130. By moving the back needle bed BB transversely, the stitch 31 a of the rear portion 130 is knitted with the heel portion 140, so the right side of the heel portion 140 is connected to the right rear end of the rear portion 130.

Then, reversing knitting from right to left, the yarns 10 and 20 are knitted on the front needle bed FB and the rear needle bed BB from the right border to the left border of the heel portion 140 to form a next course of the heel portion 140, and a plurality of live stitches (such as 31 b˜38 b) are preserved on the front needle bed FB at the left side of the rear end of the rear portion 130. It is noted that when the heel portion 140 reaches the predetermined number of stitches on the left border, the location of the leftmost stitch 41 b of the heel portion 140, which is to be knitted, corresponds to the location of the innermost (i.e. rightmost) live stitch 31 b of the live stitches 31 b˜38 b preserved at the left rear end of the rear portion 130. By moving the back needle bed BB transversely, the stitch 31 b of the rear portion 130 is knitted with the heel portion 140, so the left side of the heel portion 140 is connected to the left rear end of the rear portion 130.

The heel portion 140 is repeatedly knitted back and forth from right to left or left to right in a similar manner, wherein when the knitting of the heel portion 140 reaches the predetermined number of stitches at two opposite sides of the heel portion 140, by moving the back needle bed BB transversely, the live stitches (such as 31 a˜38 a, 31 b˜38 b) preserved on the front needle bed FB at the right and left rear ends of the rear portion 130 are sequentially and respectively knitted with the right and left sides of the heel portion 140, so the heel portion 140 and the rear portion 130 are combined to form a 3D rear shoe portion 100 a. For example, the number of the live stitches (such as 31 b˜38 b) preserved at the left rear end of the rear portion 130 is preferably the same as the number of the live stitches (such as 31 a˜38 a) preserved at the right rear end of the rear portion 130. Therefore, by repeating the double-knitting of the heel portion 140 on the front needle bed FB and the back needle bed BB as described above, the right live stitch 32 a of the rear portion 130 is knitted with the heel portion 140 at the location of the stitch 42 a at the right border, and the left live stitch 32 b of the rear portion 130 is knitted with the heel portion 140 at the location of the stitch 42 b at the left border. The right live stitch 33 a of the rear portion 130 is knitted with the heel portion 140 at the location of the stitch 43 a at the right border, and the left live stitch 33 b of the rear portion 130 is knitted with the heel portion 140 at the location of the stitch 43 b at the left border. The right live stitch 34 a of the rear portion 130 is knitted with the heel portion 140 at the location of the stitch 44 a at the right border, and the left live stitch 34 b of the rear portion 130 is knitted with the heel portion 140 at the location of the stitch 44 b at the left border. The right live stitch 35 a of the rear portion 130 is knitted with the heel portion 140 at the location of the stitch 45 a at the right border, and the left live stitch 35 b of the rear portion 130 is knitted with the heel portion 140 at the location of the stitch 45 b at the left border. The right live stitch 36 a of the rear portion 130 is knitted with the heel portion 140 at the location of the stitch 46 a at the right border, and the left live stitch 36 b of the rear portion 130 is knitted with the heel portion 140 at the location of the stitch 46 b at the left border. The right live stitch 37 a of the rear portion 130 is knitted with the heel portion 140 at the location of the stitch 47 a at the right border, and the left live stitch 37 b of the rear portion 130 is knitted with the heel portion 140 at the location of the stitch 47 b at the left border. The right live stitch 38 a of the rear portion 130 is knitted with the heel portion 140 at the location of the stitch 48 a at the right border, and the left live stitch 38 b of the rear portion 130 is knitted with the heel portion 140 at the location of the stitch 48 b at the left border. Consequently, the right border of the heel portion 140 is connected to the right rear end of the rear portion 130, so the joining line 104 a is formed. The left border of the heel portion 140 is connected to the left rear end of the rear portion 130, so the joining line 104 b is formed. As such, the heel portion 140 and the rear portion 130 are combined to form the 3D rear shoe portion 100 a, and the 3D shoe blank 100 (or 200) is completed.

Moreover, in addition to the design change in the upper portion, the 3D shoe blank of the invention may have other modifications to achieve different outer appearances or to provide other functions. As shown in FIG. 17 and FIG. 18, in a third embodiment, the 3D shoe blank 200′ further includes an extension strap 150, which is partially connected to the heel portion 140 and extends outward toward the two opposite sides of the heel portion 140. In this embodiment, the 3D shoe blank 200′ is a modification of the 3D shoe blank 200 of FIG. 7, but the extension strap 150 may be applied to the 3D shoe blank 100 of FIG. 1. The extension strap 150 is preferably a strap knitted from at least a yarn and connected to the heel portion 140. In an embodiment, the extension strap 150 is preferably double-knitted from the yarns (such as 10, 20, and/or 30) used in the previously knitting process or another yarn that is additional introduced. In another embodiment, the extension strap 150 can be double-knitted from the yarns (such as 10, 20, and/or 30) used in the previously knitting process together another yarn.

Corresponding to the design of the extension strap 150, the method of the invention further includes: double-knitting on the font needle bed FB and the back needle bed BB to form the extension strap 150, which is partially connected to the heel portion 140 and extends outward toward two opposite sides of the heel portion 140. That is, after the 3D rear shoe portion 100 a is formed, at least a yarn is provided and knitted to form the extension strap 150, so one side of the extension strap 150 is partially connected to the heel portion 140 and two ends of the extension strap 150 extend outward toward two opposite sides of the heel portion 140. For example, in the case of knitting from right to left to form the heel portion 140, after the left live stitch 38 b of the rear portion 130 is knitted with left border of the heel portion 140 at the location of the stitch 48 b, the yarn of the heel portion 140 continues to be knitted leftward for a predetermined number of stitches to form the left strap portion of the extension strap 150. Then, the knitting direction is reversed to form a next course of the left strap portion and to connect the heel portion 140. After connecting the heel portion 140, the knitting is continued rightward for a predetermined number of stitches to form the right strap portion of the extension strap 150. By repeating the knitting process back and forth, the extension strap 150 can be formed.

As shown in FIG. 19, after the 3D shoe blank 200′ is molded into a shoe body 2′, the length of the extension strap 150 is preferably long enough to surround the ankle (indicated by the arrow 2 b) of the wear's foot and to be fastened to form a bowknot. Therefore, not only the outer appearance of the shoe body 2′ can be enhanced, but the function of securing the shoe body 2′ is also provided.

As shown in FIG. 20 and FIG. 21, in a fourth embodiment, a 3D shoe blank 200″ further includes an extension portion 260, which is connected between the heel portion 140 and the extension strap 250. In this embodiment, the 3D shoe blank 200″ is a modification of the 3D shoe blank 200 of FIG. 7, but the extension strap 250 and the extension portion 260 may be applied to the 3D shoe blank 100 of FIG. 1. The extension portion 260 extends upward from the upper end of the heel portion 140, so one side of the extension strap 250 is connected to the top side of the extension portion 260 and further connected to the heel portion 140 by means of the extension strap 260. For example, the extension portion 260 and the extension strap 250 are preferably double-knitted from the yarns (such as 10, 20, and/or 30) used in the previously knitting process or another yarn. In another embodiment, the extension portion 260 and the extension strap 250 can be double-knitted from the yarns (such as 10, 20, and/or 30) used in the previously knitting process together with another yarn.

Corresponding to the design of the extension portion 260, the method of the invention further includes: double-knitting from the heel portion 140 on the font needle bed FB and the back needle bed BB to form the extension portion 260 connected between the heel portion 140 and the extension strap 250. In an embodiment, the extension portion 260 is formed by continuing knitting the yarns of the heel portion 140, so the extension portion 260 extends upward from the heel portion 140 and is connected between the heel portion 140 and the extension strap 250. For example, in the case of knitting from right to left to form the heel portion 140, after the left live stitch 38 b of the rear portion 130 is knitted with left border of the heel portion 140 at the location of the stitch 48 b, the yarn of the heel portion 140 is reverse-knitted from left to right to connect the heel portion 140 and to form the extension portion 260, and then the knitting process is continued back and forth (i.e. from right to left or left to right) to complete the knitting of the extension portion 250. After the extension portion 260 is formed, the knitting can be continued for example leftward for a predetermined number of stitches to form the left strap portion of the extension strap 250. Then, the knitting direction is reversed to form a next course of the left strap portion and to connect the extension portion 260, and the knitting is continued rightward for a predetermined number of stitches to form the right strap portion of the extension strap 250. By repeating the knitting process back and forth, the extension strap 250 can be formed.

As shown in FIG. 22, after the 3D shoe blank 200″ is molded into a shoe body 2″, the design of the extension portion 260 can increase the convenience of wearing shoes and maintain a certain distance between the extension strap 250 and the heel portion 140 to vary the outer appearance of the shoe body 2″. The length of the extension strap 250 is preferably long enough to surround the ankle (indicated by the arrow 2 b) of the wear's foot and to be fastened to form a bowknot. Therefore, not only the outer appearance of the shoe body 2″ can be enhanced, but the function of securing the shoe body 2″ is also provided.

Although the preferred embodiments of the present invention have been described herein, the above description is merely illustrative. The preferred embodiments disclosed will not limit the scope of the present invention. Further modification of the invention herein disclosed will occur to those skilled in the respective arts and all such modifications are deemed to be within the scope of the invention as defined by the appended claims. 

What is claimed is:
 1. A method for knitting a three-dimensional (3D) shoe blank by using a double-bed flat knitting machine, comprising: providing at least a first yarn on a front needle bed and a back needle bed of the double-bed flat knitting machine by skip-needle double-knitting and providing at least a second yarn on the back needle bed together to form a cast-on line; knitting the first yarn on the front needle bed and the back needle bed continuing from the cast-on line by loop-transferring and skip-needle double-knitting to form an upper portion; knitting the second yarn on the back needle bed continuing from the cast-on line by skip-needle single-knitting to form a front sole portion, wherein the upper portion and the front sole portion are alternatingly knitted, and the front sole portion is connected to the upper portion to form a pocket structure; knitting continuing from the front sole portion on the front needle bed and the back needle bed to form a rear portion, wherein when forming the rear portion, a plurality of live stitches are preserved on the front needle bed at two sides of a rear end of the rear portion; and knitting continuing from a center of the rear end of the rear portion on the front needle bed and the back needle bed by double-knitting to form a heel portion with a predetermined number of stitches, wherein when the knitting of the heel portion reaches the predetermined number of stitches at two opposite sides of the heel portion, the back needle bed moves transversely to sequentially and respectively knit the live stitches preserved on the front needle bed at the two sides of the rear end of the rear portion together with the two opposite sides of the heel portion, so the heel portion and the rear portion are combined to form a 3D rear shoe portion.
 2. The method of claim 1, further comprising: knitting continuing from one side of a rear end of the upper portion by loop-transferring and skip-needle double-knitting to form a first upper extension portion; knitting at least a third yarn continuing from the other side of the rear end of the upper portion by loop-transferring and skip-needle double-knitting to form a second upper extension portion, wherein the first upper extension portion and the second upper extension portion are spaced apart and substantially symmetric, so the first upper extension portion, the second upper extension portion, and the upper portion are combined to form an upper assembly; and knitting the second yarn on the back needle bed to form a front sole extension portion between the front sole portion and the rear portion, wherein a portion of the front sole extension portion corresponding to the first upper extension portion and the second upper extension portion is knitted by skip-needle single-knitting, and another portion of the front sole extension portion not corresponding to the first upper extension portion and the second upper extension portion is knitted by single-knitting, so the front sole portion and the front sole extension portion are combined to form a front sole assembly.
 3. The method of claim 1, wherein the rear portion is knitted from the second yarn or another yarn, or the rear portion is knitted from the second yarn together with another yarn.
 4. The method of claim 2, wherein the rear portion is knitted from the second yarn or another yarn, or the rear portion is knitted from the second yarn together with another yarn.
 5. The method of claim 1, wherein the heel portion is knitted from the second yarn or another yarn, or the heel portion is knitted from the second yarn together with another yarn.
 6. The method of claim 2, wherein the heel portion is knitted from the second yarn or another yarn, or the heel portion is knitted from the second yarn together with another yarn.
 7. The method of claim 3, wherein the heel portion is knitted from the second yarn or another yarn, or the heel portion is knitted from the second yarn together with another yarn.
 8. The method of claim 4, wherein the heel portion is knitted from the second yarn or another yarn, or the heel portion is knitted from the second yarn together with another yarn.
 9. The method of claim 1, further comprising: after the 3D rear shoe portion is formed, double-knitting on the front needle bed and the back needle bed to form an extension strap, wherein the extension strap is partially connected to the heel portion and extends outward toward the two opposite sides of the heel portion.
 10. The method of claim 9, further comprising: double-knitting from the heel portion on the front needle bed and the back needle bed to form an extension portion connected between the heel portion and the extension strap, so the extension strap is partially connected to the heel portion by means of the extension portion.
 11. The method of claim 2, further comprising: after the 3D rear shoe portion is formed, double-knitting on the front needle bed and the back needle bed to form an extension strap, wherein the extension strap is partially connected to the heel portion and extends outward toward the two opposite sides of the heel portion.
 12. The method of claim 11, further comprising: double-knitting from the heel portion on the front needle bed and the back needle bed to form an extension portion connected between the heel portion and the extension strap, so the extension strap is partially connected to the heel portion by means of the extension portion.
 13. A 3D shoe blank made by using a double-bed flat knitting machine, the 3D shoe blank being an integral knit fabric without any sewn portion, the 3D shoe blank comprising: an upper portion having two technical surfaces knitted from at least a first yarn by skip-needle double-knitting; a front sole portion connected to the upper portion by a cast-on line and two connection lines, so the front sole portion and the upper portion are connected to form a pocket structure, wherein a portion of the front sole portion corresponding to the upper portion is knitted from at least a second yarn by skip-needle single-knitting; a rear portion connected to the front sole portion; and a heel portion extending from a center rear end of the rear portion, two opposite sides of the heel portion respectively connected to a left rear end and a right rear end of the rear portion, so the heel portion and the rear portion are combined to form a 3D rear shoe portion, and two joining lines are formed between the heel portion and the rear portion on the two opposite sides of the heel portion, respectively.
 14. The 3D shoe blank of claim 13, wherein the two connection lines are connected to two ends of the cast-on line and extend outward and obliquely toward an outer side of the 3D shoe blank.
 15. The 3D shoe blank of claim 13, wherein the upper portion substantially matches the front sole portion in shape and size.
 16. The 3D shoe blank of claim 14, wherein the upper portion substantially matches the front sole portion in shape and size.
 17. The 3D shoe blank of claim 13, further comprising a first upper extension portion and a second upper extension portion connected to two sides of a rear end of the upper portion, respectively, wherein the 3D shoe blank further comprises a front sole extension portion connected between the front sole portion and the rear portion; the front sole extension portion partially corresponds to the first upper extension portion and the second upper extension portion.
 18. The 3D shoe blank of claim 17, wherein the front sole extension portion comprises covered portions masked by the first upper extension portion and the second upper extension portion and an uncovered portion exposed between the first upper extension portion and the second upper extension portion; the covered portions are knitted from the second yarn by skip-needle single-knitting and the uncovered portion is knitted from the second yarn by single-knitting.
 19. The 3D shoe blank of claim 14, further comprising a first upper extension portion and a second upper extension portion connected to two sides of a rear end of the upper portion, respectively, wherein the 3D shoe blank further comprises a front sole extension portion connected between the front sole portion and the rear portion; the front sole extension portion partially corresponds to the first upper extension portion and the second upper extension portion.
 20. The 3D shoe blank of claim 19, wherein the front sole extension portion comprises covered portions masked by the first upper extension portion and the second upper extension portion and an uncovered portion exposed between the first upper extension portion and the second upper extension portion; the covered portions are knitted from the second yarn by skip-needle single-knitting and the uncovered portion is knitted from the second yarn by single-knitting.
 21. The 3D shoe blank of claim 13, further comprising an extension strap partially connected to the heel portion and extending outward toward the two opposite sides of the heel portion.
 22. The 3D shoe blank of claim 21, further comprising an extension portion connected between the heel portion and the extension strap, so the extension strap is partially connected to the heel portion by means of the extension portion.
 23. The 3D shoe blank of claim 14, further comprising an extension strap partially connected to the heel portion and extending outward toward the two opposite sides of the heel portion.
 24. The 3D shoe blank of claim 23, further comprising an extension portion connected between the heel portion and the extension strap, so the extension strap is partially connected to the heel portion by means of the extension portion. 